Bought a Hampton HI300 insert have a 7" clay flue with 12" offset. Options for insulated liner and termination?

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.

justinandlaura

New Member
Oct 1, 2021
21
Ma
I recently purchased a lightlly used Hampton HI300 insert and liner. The liner was uninsulated, part flexible, and part rigid with a standard rain cap termination. I really don't like the way the flexible liners are corrugated and have ridges to catch creosote/debris. It just reall really seems like a fire is almost guaranteed since there is no way to really clean it well.
I'd like to install 2 stainless 45 degrees to match the offset flue and run the rigid liner/pipe up and somehow insulated the whole thing. Does anyone have any idea how this can be accomplished? Would it be legal? The Hampton manual seems to indicate single wall uninsulated pipe would be acceptable. BTW the flue is 7x11 clay so double wall pipe wont fit unfortunately. I thought about removing the clay flue and running the class a that way but im hesitant to do such a thing. I did break out and remove part of the damper throat to give room for the installation. What are peoples recommendations?
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
26,137
central pa
I recently purchased a lightlly used Hampton HI300 insert and liner. The liner was uninsulated, part flexible, and part rigid with a standard rain cap termination. I really don't like the way the flexible liners are corrugated and have ridges to catch creosote/debris. It just reall really seams like a fire is almost guranteed since there is no way to really clean it well. I'd like to install 2 stainless 45 degrees to match the offset flue and run the rigid liner/pipe up and somehow insulated the whole thing. Does anyone have any idea how this can be accomplished? Would it be legal? The Hampton manual seems to indicate single wall uninsulated pipe would be accceptable. BTW the flue is 7x11 clay so double wall pipe wont fit unfortunately. I thought about removing the clay flue and runnning the class a that way but im hesitant to do such a thing. I did break out and remove part of the damper throat to give room for the installation. What are peoples recomendations?
Class a doesn't go in a chimney it is a chimney by itself. Corregated liners are fine but heavy wall or midweight flexible liners are much smoother and more durable. For your liner you will need an oval liner so it can be insulated.
 

justinandlaura

New Member
Oct 1, 2021
21
Ma
I recently purchased a lightlly used Hampton HI300 insert and liner. The liner was uninsulated, part flexible, and part rigid with a standard rain cap termination. I really don't like the way the flexible liners are corrugated and have ridges to catch creosote/debris. It just reall really seams like a fire is almost guranteed since there is no way to really clean it well. I'd like to install 2 stainless 45 degrees to match the offset flue and run the rigid liner/pipe up and somehow insulated the whole thing. Does anyone have any idea how this can be accomplished? Would it be legal? The Hampton manual seems to indicate single wall uninsulated pipe would be accceptable. BTW the flue is 7x11 clay so double wall pipe wont fit unfortunately. I thought about removing the clay flue and runnning the class a that way but im hesitant to do such a thing. I did break out and remove part of the damper throat to give room for the installation. What are peoples recomendations?

Class a doesn't go in a chimney it is a chimney by itself. Corregated liners are fine but heavy wall or midweight flexible liners are much smoother and more durable. For your liner you will need an oval liner so it can be insulated.
So the 7" clay flue and 6" pipe with 1/2" insulation just wont fly? Can I just deform the pipe a little or do I definately need an oval liner? I really dont like that flexible crap. If the installtion manual doesnt require insulation will the inspector still require the 1/2" insulation?
 

begreen

Mooderator
Staff member
Nov 18, 2005
90,608
South Puget Sound, WA
Duraliner oval is rigid and preinsulated. It will fit in the 7x11 flue. Where would the 45º offset be occurring? At the stove?
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
26,137
central pa
So the 7" clay flue and 6" pipe with 1/2" insulation just wont fly? Can I just deform the pipe a little or do I definately need an oval liner? I really dont like that flexible crap. If the installtion manual doesnt require insulation will the inspector still require the 1/2" insulation?
The inspector won't know a thing. But do you have the required clearance to combustibles from the outside of the masonry structure? It's about safety and performance not nessecarily just passing inspection
 

justinandlaura

New Member
Oct 1, 2021
21
Ma
well the clay flue is offest from the center line of the chimney and about 30" above the stove, 12"s to the right
How bad is the creosote? Should I be concerned? I can take out the clay flue but im concerned about damaging the flue for the water heater, its right next to it.

IMG_20211017_130404994.jpg IMG_20211017_130416194.jpg IMG_20211017_130406555.jpg
 

justinandlaura

New Member
Oct 1, 2021
21
Ma
The inspector won't know a thing. But do you have the required clearance to combustibles from the outside of the masonry structure? It's about safety and performance not nessecarily just passing inspection
I have the right clearances according to installtion manual at least, I assume thats what the inspector would go by?
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
26,137
central pa
I have the right clearances according to installtion manual at least, I assume thats what the inspector would go by?
I am talking about clearances from the chimney structure itself not the stove
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
26,137
central pa
Well its running up through a masonry chimney so...? Is there someting im missing here?
The outside of that masonry chimney needs to have clearance to combustibles. 1" for external chimney 2" for an internal one
 

justinandlaura

New Member
Oct 1, 2021
21
Ma
The outside of that masonry chimney needs to have clearance to combustibles. 1" for external chimney 2" for an internal one
Still not sure where exactly you are refering to? There is wood framing and trim around the fireplace, and a hearth that extends 18" out nothing on the backside/outside of the fireplace. I have no idea how close the framing and roof is to the chimney but it had to be built to code. Does installing a new metal liner change the clearance requirements of the masonry chimney?
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
26,137
central pa
Still not sure where exactly you are refering to? There is wood framing and trim around the fireplace, and a hearth that extends 18" out nothing on the backside/outside of the fireplace. I have no idea how close the framing and roof is to the chimney but it had to be built to code. Does installing a new metal liner change the clearance requirements of the masonry chimney?
It absolutely didn't have to be built to code very very few are. And no installing a liners doesn't change the code requirements. But when you do it you are required to do it to code. Which means insulation if you don't have those clearances.

But again this isn't nearly as much about simply meeting code as it is making the install perform as well as possible and be as safe as possible. That means insulation.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
26,137
central pa
Still not understanding this? Are you saying that adding a liner will change the clearance requirements?
No adding the liner doesn't change the clearance requirements. You chimney most likely doesn't meet code now. Unless you have 1"clearance from the outside of the chimney to combustible materials other than trim on the very corners it doesn't. When you add a new liner you are required to do that to code. This means unless you have that clearance the liner must be insulated.
 

justinandlaura

New Member
Oct 1, 2021
21
Ma
It absolutely didn't have to be built to code very very few are. And no installing a liners doesn't change the code requirements. But when you do it you are required to do it to code. Which means insulation if you don't have those clearances.

But again this isn't nearly as much about simply meeting code as it is making the install perform as well as possible and be as safe as possible. That means insulation.
Ok so understand what youre saying an uninsulated liner could pose a fire hazard because of the heat radiating through the masonry? So an insulated one is required? Also how would i know what is under the hearth extension while we are on the subject of clearances. There is a plywood piece recessed down in between the floor joists that i can see in the basement, But I have no idea what there is above that. The hearth is brick, and it sits almost flush with the wood floor.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
26,137
central pa
Ok so understand what youre saying an uninsulated liner could pose a fire hazard because of the heat radiating through the masonry? So an insulated one is required? Also how would i know what is under the hearth extension while we are on the subject of clearances. There is a plywood piece recessed down in between the floor joists that i can see in the basement, But I have no idea what there is above that. The hearth is brick, and it sits almost flush with the wood floor.
The plywood can't be there. There should be no combustibles contacting the bottom of the hearth extension.

And yes you are understanding that correctly
 

justinandlaura

New Member
Oct 1, 2021
21
Ma
Ok so understand what youre saying an uninsulated liner could pose a fire hazard because of the heat radiating through the masonry? So an insulated one is required? Also how would i know what is under the hearth extension while we are on the subject of clearances. There is a plywood piece recessed down in between the floor joists that i can see in the basement, But I have no idea what there is above that. The hearth is brick, and it sits almost flush with the wood floor.

The plywood can't be there. There should be no combustibles contacting the bottom of the hearth extension.

And yes you are understanding that correctly
It doesnt seem to be touching, since it sounds hollow when i bang on it, There may be a metal plate above it that the brick where laid on? Not sure how they did it. Its extremely solid thought, there doesnt seem to be any play or give whatsoever if i bounce on it.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
26,137
central pa
It doesnt seem to be touching, since it sounds hollow when i bang on it, There may be a metal plate above it that the brick where laid on? Not sure how they did it. Its extremely solid thought, there doesnt seem to be any play or give whatsoever if i bounce on it.
The plywood is probably a form for the concrete slab under the brick
 

justinandlaura

New Member
Oct 1, 2021
21
Ma
Would i be able to remove the plywood and make it compliant or would i have to compleatly rebuild the hearth, OR put down a pad?
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
26,137
central pa
Would i be able to remove the plywood and make it compliant or would i have to compleatly rebuild the hearth, OR put down a pad?
If it was done properly you should be able to just remove the plywood
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
26,137
central pa
Would i be able to remove the plywood and make it compliant or would i have to compleatly rebuild the hearth, OR put down a pad?
But really when installing an insert you only need to meet the hearth requirements for that insert. Some require a compliant hearth for an open fireplace others only require a certain r-value
 

justinandlaura

New Member
Oct 1, 2021
21
Ma
But really when installing an insert you only need to meet the hearth requirements for that insert. Some require a compliant hearth for an open fireplace others only require a certain r-value
I think it had 1.1 r value requirement or 4" of brick, ill check it out.